Touch device and touch method

ABSTRACT

A touch device to sense and compute the coordinate of a touch object is provided. The touch device comprises a panel, a light-emitting element, an image sensor, a reflective strip and a processing unit. The panel has a sensing area surrounded by first to fourth boundaries where the first and the third boundaries define an x direction and the other two boundaries defines y direction. The light-emitting element and the image sensor are located on the first boundary with a specific distance therebetween. The reflective strip is located on the second to fourth boundaries. When the touch object touches the sensing area, a first and a second light path from the light-emitting element to the image sensor are blocked to form a real and a virtual image such that the processing unit computes the coordinate of the touch object according to the real and the virtual images. A touch method is disclosed herein as well.

RELATED APPLICATIONS

This application claims priority to Taiwan Application Serial Number099137815, filed Nov. 3, 2010, which is herein incorporated byreference.

BACKGROUND

1. Technical Field

The present disclosure relates to a touch device and a touch method.More particularly, the present disclosure relates to a touch device anda touch method utilizing a single light-emitting element and an imagesensor.

2. Description of Related Art

Touch panel has become the mainstream panel technology due toconvenience and user-friendly. Usually, the touch panel can becategorized into resistive touch panel, capacitive touch panel, acoustictouch panel, optical touch panel and electromagnetic touch paneldepending on the different sensing mechanisms.

The conventional optical touch panel utilizes two modules, each includesa sensor and a light-emitting element, disposed at two neighboringcorners of the panel respectively and reflection strips are disposed onthe other three sides of the panel. Once a stylus or a finger touchesthe panel (i.e. blocks the light paths between the light-emittingelements and the reflection strip), a dark point is generated on thesensed image of each sensor due to the blocked light paths. The positionor the coordinate of the stylus or the finger can be computed accordingto the dark points in the sensed image. However, the touch devicedeploying two light-emitting elements and two sensors is not economicalenough.

Accordingly, what is needed is a touch device and a touch methodutilizing less number of light-emitting element and sensor for realizingthe touch input mechanism to lower the cost. The present disclosureaddresses such a need.

SUMMARY

An aspect of the present disclosure is to provide a touch device. Thetouch device senses and computes a coordinate of a touch object. Thetouch device comprises a panel, a light-emitting element, an imagesensor, a reflective strip and a processing unit. The panel has asensing area successively surrounded by a first boundary, a secondboundary, a third boundary and a fourth boundary, wherein a coordinatesystem is defined by an extension direction of the first and the thirdboundaries as x-direction and an extension direction of the second andthe fourth boundaries as y-direction. The light-emitting element islocated on the first boundary and emits a first light and a secondlight. The image sensor is located on the first boundary with a specificdistance relative to the light-emitting element for sensing an image ofthe sensing area. The reflective strip is located on the second, thethird and the fourth boundaries. The processing unit is electricallyconnected to the image sensor. When the touch object touches the sensingarea, a real dark point and a virtual dark point are generated in theimage and the processing unit computes the coordinate of the touchobject according to positions of the real dark point and the virtualdark point in the image.

Another aspect of the present disclosure is to provide a touch method tosense and compute a coordinate of a touch object. The touch methodcomprises the steps as follows. (a) providing a panel having a sensingarea successively surrounded by a first boundary, a second boundary, athird boundary and a fourth boundary is provided, wherein a coordinatesystem is defined by an extension direction of the first and the thirdboundaries as x-direction and an extension direction of the second andthe fourth boundaries as y-direction; (b) disposing the touch object inthe sensing area to generate a real dark point and a virtual dark point;(c) generating an image to sense the real dark point and the virtualdark point r; (d) computing the coordinate of the touch object accordingto positions of the real dark point and the virtual dark point images inthe image.

It is to be understood that both the foregoing general description andthe following detailed description are by examples, and are intended toprovide further explanation of the disclosure as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be more fully understood by reading the followingdetailed description of the embodiments, with reference made to theaccompanying drawings as follows:

FIG. 1A is a diagram of a touch device in an embodiment of the presentdisclosure;

FIG. 1B is a diagram depicting the position of the real dark point andthe virtual dark point on the sensed image sensed by the image sensordepicted in FIG. 1;

FIG. 2 is a diagram of the touch device when the correctional procedureis performed;

FIG. 3 is the touch device in another embodiment of the presentdisclosure; and

FIG. 4 is a flow chart of a touch method in an embodiment of the presentdisclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to the present embodiments of thedisclosure, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers are used in thedrawings and the description to refer to the same or like parts.

Please refer to FIG. 1A. FIG. 1A is a diagram of a touch device 1 in anembodiment of the present disclosure. The touch device 1 is able tosense and compute the position or the coordinate of a touch object orpoint 2. The touch device 1 comprises a panel 10, a light-emittingelement 12, an image sensor 14, a reflective strip 16 and a processingunit (not shown).

The panel 10 has a sensing area 100 such that the touch object 2 can bedisposed therein. The sensing area 100 is surrounded by a first boundary101, a second boundary 103, a third boundary 105 and a fourth boundary107. A coordinate system is defined with the extension direction of thefirst and the third boundaries 101 and 105 as x direction, the extensiondirection of the second and the fourth boundaries 103 and 107 as ydirection, and the left-top corner of the panel 10 as origin point. Thecoordinate of the light-emitting element 12 (x2, y2), the coordinate ofthe image sensor 14 (x1, y1), the width W of the panel and the specificdistance D between the image sensor 14 and the light-emitting element 12are all known parameters which can be preset when the touch device 1 isassembled.

The light-emitting element 12 and the image sensor 14 can be located onthe first boundary 101 or located on a position at a distance a certaindistance from the first boundary 101. In the present embodiment, thelight-emitting element 12 and the image sensor 14 are both located onthe first boundary 101 with a specific distance D along the x directiontherebetween. The specific distance is selected such that the imagesensor 14 is able to receive the reflected light from the reflectivestrip 16, where the reflected light is generated according to lightemitted by the light-emitting element 12.

The image sensor 14 performs the sensing process to sense the touchobject 2 within the sensing area 100 (by retrieving the image comprisingthe touch object 2). Substantially, due to the touch object 2 could beplaced at any position within the sensing area 100, a suitable (largeenough) angle of view is necessary for the image sensor 14 to sense thewhole sensing area 100. In an embodiment, if the light-emitting element12 and the image sensor 14 are located on an end of the first boundary101 (or a corner of the panel 10), the angle of view of the image sensor14 has to be larger than or equal to 90 degrees to sense the wholesensing area 100. In the present embodiment, the image sensor 14 isplaced at about the middle of the first boundary 101, the angle of viewof the image sensor 14 has to be 180 degrees for sensing the wholesensing area 100.

The reflective strip 16 is located on the second boundary 103, the thirdboundary 105 and the fourth boundary 107 to reflect the light from thelight-emitting element 12. The reflective strip 16 can reflect theincident light concentratedly along the incident path back. The term“concentratedly” means that most energy of the incident light isreflected back to the light-emitting element 12 along the incident path.However, it is impossible to reflect 100% of the energy back to thelight-emitting element 12 due to the limit of physics. In other words, asmall portion of the energy, not reflected back to the light-emittingelement 12 along the incident path, is scattered to a neighboring areaof the light-emitting element 12, and the farther between theneighboring area and the light-emitting element 12, the more the energyreduces. In the present embodiment, the image sensor 14 utilizes thelight not reflected back to the incident path (i.e. the scatteredreflected light) to compute the coordinate of the touch object 2. Hence,the distance D between the image sensor 14 and the light-emittingelement 12 cannot be too large. If distance D between the image sensor14 and the light-emitting element 12 is too large, the image sensor 14is not able to sense the reflected, light since the energy of thereflected light scattered to the image sensor 14 is too low. In apreferable embodiment, the range of the specific distance D along the xdirection between the image sensor 14 and the light-emitting element 12is about 5 mm to 20 mm such that the light reflected to the image sensor14 has enough energy for the image sensor 14 to perform the sensingprocess. The processing unit is electrically connected to the imagesensor 14. In an embodiment, the processing unit is an internal moduleof the panel 10 or is integrally formed with the image sensor 14(integrated with the image sensor 14). The processing unit can convertthe position of the touch object 2 within the sensed image to thecoordinate of the touch object 2 in the sensing area 2.

When the touch object (a stylus or a finger) touches the sensing area100, the light from the light-emitting element 12 would be blocked. Indetails, as described previously, if the touch object 2 is absent, afirst light 11 would be reflected at the first reflection point P1 onthe reflective strip 16, most energy is reflected back to thelight-emitting element 12 along the incidental path and a small portionof the other energy (those not reflected back to the light-emittingelement 12) is reflected to the image sensor 14 along a first light path13 and sensed by the image sensor 14. Besides, a second light 15 wouldbe reflected at the second reflection point P2 on the reflective strip16, most of the energy is reflected back to the light-emitting element12 along the incidental path, and a small portion of the other energy(those not reflected back to the light-emitting element 12) is reflectedto the image sensor 14 along a second light path 17 and is sensed by theimage sensor 14.

However, once the touch object 2 touches the sensing area 100, whichblocks both the first light path 13 and directly blocks the second light15 such that a real dark point 20 corresponding to the first light path13 and a virtual dark point 22 corresponding to the second light path 17are formed on the sensed image 21 of the image sensor 14 as shown inFIG. 1B. Afterwards, the processing unit can compute the coordinate ofthe touch object 2 on the coordinate system according to the positionsof the real and the virtual dark points 20 and 22 on the sensed image21.

Before describing how to compute the coordinate of the touch object 2,it is necessary to understand how optical procedure is performed on thetouch device 1 to obtain a regression curve or optical data such thatsensed angles can be computed according to the regression curve and theposition of the dark points on the sensed image 21. The so-called sensedangles are the angles relative to the x direction. Please refer to FIG.2. FIG. 2 is a diagram of the touch device 1 when optical procedure isperformed. The light-emitting element 12 and the image sensor 14 aredisposed on a corner of the panel 10. The touch object 2 is first placedon a path L1 corresponding to a predetermined first sensed angle θ10 toform a dark point P10 on the sensed image 21. Then, the touch object 2is placed on a path L2 corresponding to a predetermined first sensedangle θ20 to form a dark point P20 on the sensed image 21. The touchobject 2 is kept placing at different positions each on a pathcorresponding to a specific sensed angle until the touch object 2 isplaced on a path L8 corresponding to a predetermined first sensed angleθ80 to form a dark point P80 on the sensed image 21. Hence, a group ofimages comprises the dark points (θ10, θ20, . . . , θ80) respectivelycorresponding to different sensed angles (θ10, θ20, . . . , θ80) areobtained. Then, the two groups (positions of the dark points andcorresponding sensed angles) of data are used to determine a regressioncurve or a fitting curve, i.e. the calibration data. The calibrationdata is stored in the touch device 1. Consequently, once the dark pointon the sensed image 21 is known, the sensed angle can be determined bythe position of the dark point through the regression curve. It'snoticed that the number of the predetermined sensed angles used toperform the calibration procedure is not limited to eight. The number ofthe predetermined sensed angles can be determined depending on thepractical situation. With more predetermined sensed angles, the computedregression curve is closer to the practical angle.

After the calibration procedure is performed, the processing unit storesthe calibration data (i.e. the regression curve) that stands for therelation between the positions of the dark points in the sensed image 21and the sensed angles. It's noticed that since the light-emittingelement 12 and the image sensor 14 are placed on the top-right corner ofthe panel 10 in FIG. 2, 90 degrees for the angle of view of the imagesensor 14 is enough. However, for the angle of view of the image sensor14 having 180 degrees, as depicted in FIG. 1A, the calibration procedureis still similar to the procedure described above.

Please refer to FIG. 1A again. After retrieving the stored calibrationdata, the processing module computes a first sensed angle of the firstlight path 13 and a second sensed angle of the second light path 17according to the positions of the real dark point 20 and the virtualdark point 22 on the sensed image 21 respectively. Assuming that thefirst sensed angle of the first light path 13 is θ1 and the secondsensed angle of the second light path 17 is θ2.

As described above, The coordinate of the light-emitting element 12 (x2,y2), the coordinate of the image sensor 14 (x1, y1), the width W of thepanel and the specific distance D between the image sensor 14 and thelight-emitting element 12 are all known parameters, wherein

y1=y2;

x1−x2=D;

The processing unit can compute the coordinate (x3, y3) of the firstreflection point P1 and the coordinate (x4, y4) of the second reflectionpoint P2:

tan θ₁=w/(x₁−x₃)

tan θ₂=w/(x₁−x₄)

where

y3=y4;

y3−y1=W

Accordingly, (x1, y1), (x2, y2), (x3, y3) and (x4, y4) are known. Then,the angle θ₃ of the second light 15 relative to the x direction can becomputed by the following equation:

θ₃=tan⁻¹[(y ₄ −y ₂)/(x ₄ −x ₂)]

Finally, two linear equations can be obtained according to the knownangles θ₁ and θ₃, where (x, y) is the coordinate of the touch object 2on the sensing area 100:

y−y ₁=(tan θ₁)(x ₁ −x)

y−y ₂=(tan θ₃)(x−X ₂)

By solving the set of linear equations, the solution (x, y), i.e. thecoordinate of the touch object 2 on the sensing area, is obtained.

By keeping a distance between the light-emitting element and the imagesensor, the image sensor of the touch device of the present disclosurecan sense the real dark point and the virtual dark point when the touchobject touches the sensing area and blocks two light paths. Thecoordinate of the touch object can thus be computed with less number ofthe light-emitting element and the image sensor.

Please refer to FIG. 3. FIG. 3 is the touch device 1 in anotherembodiment of the present disclosure. Similar to the touch devicedepicted in FIG. 1, the touch device 1 in FIG. 3 comprises a panel 10, alight-emitting element 12, an image sensor 14, a reflective strip 16 anda processing unit (not shown). In the present embodiment, the touchdevice 1 further comprises an auxiliary light-emitting element 3.

Similar to the light-emitting element 12, when the touch object 2touches the sensing area 100, a third light path 33 formed by reflectinga third light 31, which is generated from the auxiliary light-emittingelement 3, on the reflective strip 16 to the image sensor 14 is blockedto generate an auxiliary real dark point, and a fourth light 35,generated from the auxiliary light-emitting element 3, is directlyblocked such that an auxiliary virtual dark point is generated. Theimage sensor 14 senses an auxiliary real dark point and an auxiliaryvirtual dark point into the sensed image 21, then the processing unitcomputes the coordinate of the touch object 2 on the coordinate systemaccording to the positions of the auxiliary real image and the auxiliaryvirtual image on the sensed image 21.

It's noticed that in the present embodiment, the image sensor 14 stillsenses light from the light-emitting element 12. In other words, twolight-emitting elements 12 and 3 and one image sensor 14 are used tocompute the coordinate of the touch object 2 in the present embodiment.The results obtained respectively are then averaged or weightedlyaveraged to improve the accuracy of the sensing result. However, whenthe light-emitting element 12 and the auxiliary light-emitting element 3are both presented as shown in FIG. 3, they have to be drivennon-simultaneously such that the virtual dark point generated by one ofthe light-emitting elements would not disappear as a result oflight-compensation by the other light-emitting element. In other words,when light-emitting element 12 emits the light, the auxiliarylight-emitting element 3 should be turned off, and when the auxiliarylight-emitting element 3 emits light-emitting element the light, thelight-emitting element 12 should be turned off, thus avoiding theunnecessary lights compensate the blocked light path of the virtual darkpoint resulting in only the real dark point generated on the sensedimage 21.

Please refer to FIG. 4. FIG. 4 is a flow chart of a touch method in anembodiment of the present disclosure. The touch method is adapted to thetouch device 1 depicted in FIG. 1A and FIG. 3 to sense the touch object2 and compute the coordinate of the touch object 2. The touch methodcomprises the steps as follows. (The steps are not recited in thesequence in which the steps are performed. That is, unless the sequenceof the steps is expressly indicated, the sequence of the steps isinterchangeable, and all or part of the steps may be simultaneously,partially simultaneously, or sequentially performed).

In step 401, the panel 10, the light-emitting element 12, the imagesensor 14 and the reflective strip 16 are provided. The image sensor 14and the light-emitting element 12 are dispatched with a specificdistance D therebetween. The width of the panel 10 is W. The panel 10has the sensing area 100 surrounded by the first boundary 101, thesecond boundary 103, the third boundary 105 and the fourth boundary 107.The extension direction of the first and the third boundaries 101 and105 defines an x-direction and the extension direction of the second andthe fourth boundaries 103 and 107 defines a y-direction. With thex-direction and y-direction, the origin point is chosen to be theleft-top corner of the panel 10 to define the coordinate system. Aprocessing unit can be further provided in step 401. The coordinate ofthe light-emitting element 12 (x2, y2) and the coordinate of the imagesensor 14 (x1, y1) are known in step 401 already.

In step 402, the touch object 2 is disposed in the sensing area 100 suchthat a first light path 13, formed by reflecting a first light 11generated from the light-emitting element 12 on a first reflection pointP1, to the image sensor 14 is blocked to generate a real dark point, anda second light 15 is directly blocked such that a virtual dark point isgenerated on a second light path 17 formed by reflecting the secondlight 15 on a second reflection point P2 to the image sensor 14.

In step 403, the first sensed angle of the real dark point (on the firstlight path 13) θ₁ relative to the x direction and the second sensedangle of the virtual dark point (on the second light path 17) θ₂relative to the x direction are computed respectively. The computingprocess in step 403 is performed according to the calibration data,wherein in an embodiment, the calibration data is a regression curve ora fitting curve. In an embodiment, the calibration data is pre-stored inthe image sensor 14 or the processing unit.

In step 404, the coordinate (x3, y3) of the first reflection point P1and the coordinate (x4, y4) of the second reflection point P2 arecomputed. The computing process in step 404 can be performed with theuse of triangulation according to the sensed angles θ₁, θ₂, the width Wof the panel 10 and the coordinate of the image sensor 14.

In step 405, the angle θ₃ of the second light 15 relative to the xdirection is computed. The computing process in step 405 can beperformed with the use of triangulation according to the coordinate ofthe second reflection point P2 (x4, y4) and the coordinate of thelight-emitting element 12 (x2, y2).

In step 406, the coordinate of the touch object 2 (x, y) is computed.The computing process in step 406 can be performed with the use oftriangulation according to the coordinate of the light-emitting element12 (x2, y2), the coordinate of the image sensor 14 (x1, y1), the angleθ₃ and the sensed angle θ₁.

In an embodiment, the auxiliary light-emitting element 3 can be providedin step 401 as well to let the touch object 2 block the third light path33 and the fourth light path 37 in step 402. The image sensor 14 canfurther sense the real dark point and virtual dark point due to theauxiliary light-emitting element 3 to compute the coordinate of thetouch object 2, thus improving the accuracy of the sensing result.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentdisclosure without departing from the scope or spirit of the disclosure.In view of the foregoing, it is intended that the present disclosurecover modifications and variations of this disclosure provided they fallwithin the scope of the following claims.

1. A touch device for sensing and computing a coordinate of a touchobject, wherein the touch device comprises: a panel having a sensingarea surrounded by a first boundary, a second boundary, a third boundaryand a fourth boundary, wherein a coordinate system is defined by anextension direction of the first boundary and the third boundary defineas x-direction and an extension direction of the second boundary and thefourth boundary as y-direction; a light-emitting element located on thefirst boundary and emit a first light and a second light; an imagesensor located on the first boundary with a specific distance relativeto the light-emitting element for sensing an image of the sensing area;a reflective strip located on the second, the third and the fourthboundaries; and a processing unit electrically connected to the imagesensor; wherein when the touch object touches the sensing area, a realdark point and a virtual dark point are generated in the image; whereinthe processing unit computes the coordinate of the touch object on thecoordinate system according to positions of the real dark point and thevirtual dark point in the image.
 2. The touch device of claim 1, whereinthe real dark point is formed by blocking a first light path formed byreflecting the first light on a first reflection point of the reflectivestrip, and a virtual dark point is formed by a second light path formedby reflecting the second light on a second reflection point of thereflective strip; wherein the second light is blocked directly by thetouch object before being reflected.
 3. The touch device of claim 2,wherein the processing module has a calibration data, which is arelationship between position in the image and a sensed angle.
 4. Thetouch device of claim 3, wherein the sensed angle is an angle relativeto the x direction.
 5. The touch device of claim 3, wherein theprocessing module computes a first sensed angle of the first light pathand a second sensed angle of the is second light path according to thecalibration data.
 6. The touch device of claim 5, wherein the processingmodule further computes a first coordinate of the first reflection pointand a second coordinate of the second reflection point according to thefirst sensed angle and the second sensed angle.
 7. The touch device ofclaim 6, wherein the processing module further computes an angle of thesecond light relative to the x direction according to the firstcoordinate and the second coordinate.
 8. The touch device of claim 7,wherein the processing module further computes the coordinate of thetouch object according to the angle of second light.
 9. The touch deviceof claim 2, further comprising an auxiliary light-emitting element,wherein the light-emitting element and the auxiliary light-emittingelement are driven non-simultaneously.
 10. The touch device of claim 1,wherein the specific distance is between 5 mm to 20 mm.
 11. The touchdevice of claim 1, wherein an angle of view the image sensor is largerthan or equal to 90 degrees.
 12. A touch method to sense and compute acoordinate of a touch object, wherein the touch method comprises thesteps of: (a) providing a panel having a sensing area surrounded by afirst boundary, a second boundary, a third boundary and a fourthboundary, wherein a coordinate system is defined by an extensiondirection of the first boundary and the third boundary as x-directionand an extension direction of the second boundary and the fourthboundary as y-direction; (b) disposing the touch object in the sensingarea to generate a real dark point and a virtual dark point; (c)generating an image for sensing the real dark point and the virtual darkpoint; and (d) computing the coordinate of the touch object according topositions of the real dark point and the virtual real dark in the image.13. The touch method of claim 12, further comprising a step of:providing a calibration data, which is a relationship between positionin the image and a sensed angle.
 14. The touch method of claim 13,wherein the sensed angle is an angle relative to the x direction.